JPS58127748A - Flame-retardant resin composition - Google Patents

Abstract

PURPOSE:To provide a magnetic powder-contg. flame-retardant resin compsn., by incorporating a flame retarder composed of brominated polystyrene and antimony trioxide in combination. CONSTITUTION:10-60wt% mixture consisting of 100pts.wt. polyolefin resin such as polypropylene resin powder, 30-80wt% brominated polystyrene of the formula (wherein x is 1-5; n is a 2 or more) and 10-40pts.wt. antimony trioxide, is mixed with 90-40wt% magnetic powder such as ferrite powder or a rare earth metal/coablt alloy powder.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to highly flame retardant compositions comprising magnetic powders, polyolefin resins and specific combinations of flame retardants. More specifically, when making a polyolefin resin filled with a large amount of magnetic powder flame retardant, a combination of brominated polystyrene and antimony trioxide is used as a flame retardant to achieve a high degree of flammable combustion resistance and a high degree of flame retardancy. The present invention relates to an extremely useful flame-retardant composition that also has flameless combustion resistance.

Compositions made by filling a synthetic resin with a large amount of magnetic powder are widely used as magnetic plastics, and compositions using polyolefin resins are particularly useful because they are inexpensive and have good moldability. In recent years, there has been a demand for improved flame retardancy of such magnetic planutics in applications such as electrical and electronic parts. However, polyolefin resins filled with a large amount of magnetic powder can be prepared using known general methods such as decabromidiphenylethyl, hexabromobenzene, or [Dechlorane J (registered trademark: Hooker Chemical & Plastics Corporation)]. f
fU) The method of adding general organic halogen compounds and antimony oxide to flame retardation is still insufficient to obtain a high degree of flame retardancy within a practical range.

That is, although it is relatively easy to achieve a high degree of flammable combustion resistance using the above method, a resin composition filled with a large amount of magnetic powder remains red-hot even after the flame is extinguished. Flameless combustion (referred to as blowing) tends to last for a long time, making it impossible to obtain flame retardance that is practically satisfactory. In order to eliminate such disadvantages, methods are sometimes adopted in which a larger amount of flame retardant is used, talc, or other fillers are added, but the mechanical strength of the final composition is reduced and the moldability is reduced. However, it is not satisfactory in practical terms because it has disadvantages such as deterioration of the process and high cost.

The inventors of the present invention have conducted extensive research in order to overcome these difficulties and develop a material that has both a high degree of flammable combustion resistance and a short glow time, that is, flameless combustion resistance. It has been discovered that when making a filled polyolefin resin flame retardant, a specific combination of flame retardants can achieve a specific high degree of flame retardancy, and the problems of the above-mentioned known techniques can be solved at once. This led to the present invention.

The composition according to the present invention consists of: 60-10% by weight of a mixture consisting of 30-80 parts by weight of brominated polystyrene represented by the number) and 10-40 parts by weight of antimony trioxide; and 40-90% by weight of magnetic powder. It is a flame retardant resin composition consisting of.

The polyolefin resin used in the present invention is polyethylene,
Polypropylene, polybutene-1, ethylene-propylene copolymer, ethylene-vinyl acetate copolymer, ethylene-vinyl chloride copolymer, other synthetic resins whose main constituents are olefin monomer units, or synthetic resins thereof It is a mixture. For the purpose of improving the properties of the final composition, polymeric materials other than the above-mentioned polyolefin resins may be added. From a practical point of view, polypropylene resin has good moldability,
It is particularly preferred because it has a good balance between heat resistance and economic efficiency. Furthermore, in the final composition according to the present invention, it is desirable that each component is uniformly dispersed, and any shape of polyolefin resin can be used as long as it is sufficiently mixed and kneaded; however, from an industrial point of view, Powdered polyolefin resins are preferred.

In the present invention, powdered polypropylene resin is most preferably used.

Diffuses preferably used in the composition of the present invention (in the formula:
X is an integer of 1 to 5 and represents the degree of bromination, and n is an integer of 2 or more and represents the degree of polymerization). Brominated polystyrene is industrially available with a degree of bromination of 1 to 5 and a degree of polymerization n of 2 or more. Generally, the higher the degree of bromination, the higher the flame retardant ability, but it is not economical. This becomes difficult to obtain. Those having an average degree of bromination of 2 to 4 are easily available industrially and are preferably used. Brominated polystyrene has good flame retardant properties as long as it is a polymer, but if it has an extremely low degree of polymerization, it will be similar to common flame retardants such as hexabromobenzene or decabrom diphenyl oxide. However, it is desirable to have a degree of polymerization of about 100 or more, although it cannot be further specified because it may cause problems of bleeding and will vary depending on the composition of the final composition, conditions of use, etc. If the amount of brominated polystyrene used is less than 30 parts by weight based on the polyolefin resin, flammable combustion resistance will be impaired, and if it exceeds 80 parts by weight, mechanical properties and heat resistance may be adversely affected. . Therefore, in the composition of the present invention, it is preferable to use 30 to 80 parts by weight of brominated polystyrene per 100 parts by weight of polyolefin resin, more preferably 40 to 6 parts by weight.
0 parts by weight is used. Further, various flame retardants other than brominated polystyrene may be added and used in small amounts in combination without impairing the specific effects of brominated polystyrene, which will be described later.

Another component of the flame retardant is antimony dioxide.

When antimony trioxide is mixed with the brominated polystyrene mentioned above, it exhibits a synergistic effect on flammable combustion resistance. The amount used may be 1 to 2 to 5 brominated polystyrene by weight, but preferably 1 to 72 to 3 brominated polystyrene. Therefore,
In the present invention, 10 to 4
0 parts by weight are used.

As the magnetic powder used in the present invention, powdered powders of various magnetic materials can be used depending on the intended use of the final composition. Typical examples include barium ferrite, strontium ferrite, other magnetoplumbite-type ferrite powders, manganese-zinc ferrite, nickel-zinc fephite, manganese-magnesium ferrite, other spinel-type ferrite powders, samarium-cobalt alloys, praseodymium-cobalt. Examples include Mitsushi metal-cobalt alloy, other rare earth metal-cobalt alloy powder, aluminum-nickel-cobalt alloy powder, and iron-chromium-cobalt alloy powder. These magnetic powders may be used alone or in combination of two or more types, if necessary. Among the above magnetic powders, ferrite powders such as magnetoplumbite ferrite and spinel ferrite, and rare earth metal-cobalt alloy powders are preferably used from the viewpoint of economic efficiency, magnetic performance, or industrial availability. . A composition using magnetoplumbite ferrite powder can be used as a general-purpose flexible magnet, and a composition using spinel ferrite powder can be used as a radio wave absorber material. Compositions using rare earth metal-cobalt alloy powders are used as ultra-high performance magnets. In particular, magnetoplumbite type ferrites such as barium ferrite and strontium ferrite have a wide range of applications and are particularly important. The preferred content of these magnetic powders in the composition of the present invention cannot be specified as it varies depending on the specific gravity of the magnetic powder used or the composition of the remaining components, but if it is less than 40% by weight, On the other hand, if it exceeds 90% by weight, it may lead to a decrease in moldability and mechanical strength.
~90% by weight is preferred, and 50-90% by weight is particularly preferred.

For the purpose of improving the properties of the compositions of the present invention, for example, heat stabilizers, processability improvers, dispersion improvers, mechanical strength improvers and other modifying additives are specifically added according to the present invention. It can be used within a range that does not impair the high degree of flame retardancy achieved. In particular, it is desirable to add a heat stabilizer and a processability improver to improve the heat stability during molding, heat aging resistance, and moldability.

Furthermore, when mixing and kneading various components to prepare the composition of the present invention, any method generally employed for preparing synthetic resin compositions may be used. For example, the mixture may be uniformly dispersed using a high-speed mixer, then melt-kneaded using a heated roll or an extruder, and then cut into pellets to provide a predetermined molded structure as a raw material.

Next, the effects of the present invention will be explained.

As mentioned above, a composition in which a polyolefin resin filled with a large amount of magnetic powder is made flame retardant using a commonly known flame retardant has good flammable combustion resistance, but the blowing time is long, making it difficult to put into practical use. ” - indicates a tendency to not have satisfactory flame retardancy. The reason for this is not necessarily clear, but the large amount of magnetic powder filled in is heated by the combustion heat during flaming combustion and becomes part of the core of flameless combustion, which not only causes the blowing to continue for a long time. It is thought that the carbonized residue produced by the decomposition of the halogen flame retardant itself remains red-hot and becomes the cause of blowing.

Among various halogen flame retardants, there are those with a large amount of decomposition and carbonized residue and those with a small amount of decomposition and carbonization residue, but the brominated polystyrene used in the composition of the present invention has particularly little residual water, which is an inconvenience that promotes flameless combustion, and is flame resistant. It is surmised that it was possible to simultaneously provide combustibility and suppress blowing in a short period of time. Such an effect is an entirely unexpected phenomenon, even though brominated polystyrene belongs to the group of aromatic nuclear brominated compounds whose chemical structure is seemingly similar to other typical flame retardants such as hexabromobenzene and decabromodiphenyl ether. .

Thus, the composition according to the present invention is subjected to molding and is used as a plastic magnetic molded product for general use as parts for electrical and electronic equipment, measuring instruments, rotating machines, and the like. In particular, it has a high degree of flame retardancy, which has been difficult to achieve in the past, so it has a wide range of applications and is extremely useful.

The present invention will be explained below with reference to Examples.

Example 1 30% by weight of a mixture consisting of 100 parts by weight of powdered polypropylene resin, 40 parts by weight of brominated polystyrene, 14 parts by weight of antimony trioxide, 2 parts by weight of a stabilizer and 0.5 parts by weight of a processability improver and barium ferrite powder. After putting 70% by weight into a 101 super mixer and stirring and mixing,
The mixture was melt-kneaded using an 8-inch heated roll to form pellets. This pellet is molded using an injection molding machine, and
A test piece measuring 1/2 x 1/16 was obtained. This was subjected to a combustion test according to the vertical combustion test method of UL-94, and the results shown in Table 1 were obtained.

The results show that the sample of this example is excellent in both flammable combustion resistance and blowing, and is evaluated as UL-94V-Q.

Examples 2 to 7 Samples were obtained in the same manner as in Example 1 by changing the proportions of brominated polystyrene, antimony trioxide, and barium ferrite. As shown in Table 1, the flame retardancy-11- property evaluation results are all UL-94.
At V-0! It's extremely good.

Comparative Examples 1 to 3 In place of using brominated polystyrene in Example 1,
Hexabromobenzene and "Dechlorane Plus" respectively
Test pieces were obtained in the same manner except that decabromidiphenyl ether (a registered trademark of Hooker Chemical and Plastics Corporation) or decabromidiphenyl ether was used.

The flame retardant evaluation results for each sample are shown in Table 1. The samples were prepared in the same manner as in Example 1, except that the amounts of hydrobrominated polystyrene and antimony trioxide were 20 parts by weight and 8 parts by weight, respectively, outside the scope of the claims of the present invention. A test piece was obtained and subjected to a combustion test.

The test piece burned up to the clamp, and its flame retardancy was insufficient.

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Claims (1)

Scope of Claims: A mixture of 60 to 80 parts by weight of brominated polymethyleff represented by the formula (wherein X is an integer of 1 to 5, and n is an integer of 2 or more) and 10 to 40 parts by weight of antimony trioxide 10
% by weight and 40 to 90% by weight of magnetic powder. 2. The composition according to claim 1, wherein the magnetic powder is a ferrite powder. 3. The composition according to claim 1, wherein the magnetic powder is a rare earth metal-Kobaf 1/2) alloy powder. 4. The composition according to claim 1, 2 or 3, wherein the polyolefin resin is a powdered polypropylene resin.